Technical Abstract:
Smoked salmon can be contaminated with Listeria monocytogenes. It is important to develop effective control measures by identifying factors that would control L. monocytogenes growth in smoked salmon. The purpose of this study was to evaluate the effect of salt, a liquid smoke, storage temperature and their interactions on L. monocytogenes in simulated smoked salmon. A 6-strain mixture of L. monocytogenes (2 to 3 log cfu/g) was inoculated into cooked salmon containing 0-10% NaCl and 0-0.4% liquid smoke (0-34 ppm phenol), and the samples were stored at temperatures ranging from 0 to 25 degree C. Lag phase duration (LPD, h), growth rate (GR, log cfu/h) and maximum population density (MPD, log cfu/g) of L. monocytogenes in salmon as affected by the concentrations of salt and phenol, storage temperature and their interactions were analyzed. Results showed that L. monocytogenes was able to grow in salmon containing the concentrations of salt and phenol commonly found in smoke salmon at the prevailing storage temperatures. The growth of L. monocytogenes was affected significantly (p<0.01) by salt, phenol, storage temperature and their interactions. Higher levels of salt or lower storage temperatures extended the LPD and reduced the GR. Higher levels of phenol etended the LPD of L. monocytogenes, particularly at lower storage temperatures. However, its effect on reducing the GR of L. monocytogenes was only observed at higher salt concentrations (>6%) at refrigerated and mild abuse temperatures (<10 degree C). The MPD, which generally reached 7-8 log cfu/g in salmon that supported L. monocytogenes growth, was not affected by the salt, phenol and storage temperature. The data from this study would be useful for estimating the behavior of L. monocytogenes in smoked salmon.